doylee4693
Tahoe User
Any ideas? Mechanic says tranny mounts look good,tranny fluid is good.
clunk on downshift into second gear
- Thread starter doylee4693
- Start date
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GM says it is normal:
#01-07-30-042E: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise - (May 21, 2007)
Subject: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise
Models: 2008 and Prior Passenger Cars and Light Duty Trucks
with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32, M70)
--------------------------------------------------------------------------------
This bulletin is being revised to add the 2008 model year and 4L70E transmissions. Please discard Corporate Bulletin Number 01-07-30-042D (Section 07 - Transmission/Transaxle).
--------------------------------------------------------------------------------
Important: For 2005 model year fullsize utilities and pickups, refer to Corporate Bulletin 05-07-30-012.
Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.
During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case.
This is a normal condition. No repairs should be attempted.
#01-07-30-042E: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise - (May 21, 2007)
Subject: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise
Models: 2008 and Prior Passenger Cars and Light Duty Trucks
with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32, M70)
--------------------------------------------------------------------------------
This bulletin is being revised to add the 2008 model year and 4L70E transmissions. Please discard Corporate Bulletin Number 01-07-30-042D (Section 07 - Transmission/Transaxle).
--------------------------------------------------------------------------------
Important: For 2005 model year fullsize utilities and pickups, refer to Corporate Bulletin 05-07-30-012.
Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.
During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case.
This is a normal condition. No repairs should be attempted.
Physh1
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Mine does that...since day 1. Mechanics at my work say it's normal & not to worry as long as a) trans isn't slipping, b) fluid lever is good, & c) fluid is clean.
Cameron
Cameron
doylee4693
Tahoe User
Its good to know nothing is wrong with it,just wish I could fix it.Seems to be happening more and more lately......might be because its cold? Used to just happen one every 5 times,now it pretty much happens everytime.
ScottL4619
Full Access Member
Mine does this all the time, especially when cold and accelerating lightly. It drives me insane! It is so bad that when I have passengers in my truck, they ask if something is wrong when it happens. I also think it is ridiculous that GM thinks a clunk that loud is "normal" and cannot be fixed.
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